The present application relates to expandable stents and, more particularly, to expandable stents with flexible hinges.
It is desirable to provide flexibility in stents to facilitate introduction of the stent into vessels that are difficult to reach. Often, however, characteristics of the stent that provide longitudinal flexibility that is desirable when introducing the stent into the vessel can be disadvantageous in terms of keeping the stent in an expanded condition. For example, stents formed from interconnected rings with closed cell structures or generally diamond-shaped cells are typically less flexible than stents formed from one or more helices, but are usually more uniformly and consistently expandable than helical stents. It is desirable to provide a stent with substantial flexibility that is adapted to be expanded in a uniform and consistent fashion.
In WO 03/015664, which is incorporated by reference, a stent having interconnected struts with openings for drug delivery is disclosed. However, elements for bridging the struts are generally thinner and spaced further apart than the struts. Thus, for such drug-eluting stents, the bridging element can provide an area of reduced or less consistent drug delivery. It is desirable to provide a drug-eluting stent in which areas of reduced or less consistent drug delivery can be reduced.
In accordance with an aspect of the present invention, a helical stent comprises at least one helical winding, each helical winding comprising a plurality of alternating long struts and short struts, ends of at least some of the long struts being joined to an end of an adjacent short strut by a flexible hinge arrangement, the struts being substantially rigid, and at least one interconnection member connecting a hinge arrangement on one turn of the at least one winding with a hinge arrangement on an adjacent turn of the at least one winding, wherein fewer than all hinge arrangements on the at least one helical winding are connected to other hinge arrangements by an interconnection member.
In accordance with another aspect of the present invention, a helical stent comprises at least one helical winding, each helical winding comprising a plurality of struts, ends of the struts being joined to an end of an adjacent strut by a flexible hinge arrangement, the struts being substantially rigid, and at least one interconnection member connecting a hinge arrangement on one turn of the at least one winding with a hinge arrangement on an adjacent turn of the at least one winding, wherein fewer than all hinge arrangements on the at least one helical winding are connected to other hinge arrangements by an interconnection member.
In accordance with another aspect of the present invention, a helical stent comprises at least one helical winding, each helical winding comprising a plurality of pairs of long struts and short struts, the struts being substantially rigid, and a plurality of flexible hinge arrangements, ends of at least some of the long struts being joined to an end of an adjacent short strut by the hinge arrangements, each of the plurality of flexible hinge arrangements comprising a substantially rigid connecting member and a first flexible hinge between the connecting member and a long strut and a second flexible hinge between the connecting member and a short strut.
In accordance with another aspect of the present invention, a helical stent comprises at least one helical winding, each helical winding comprising a plurality of pairs of long strut assemblies and short strut assemblies, the struts being substantially rigid, the long strut assembly comprising at least two struts and being longer than the short strut assembly, and a plurality of flexible hinge arrangements, ends of at least some of the long strut assemblies being joined to an end of an adjacent short strut assembly by the hinge arrangements, each of the plurality of flexible hinge arrangements comprising a substantially rigid connecting member and a first flexible hinge between the connecting member and a long strut assembly and a second flexible hinge between the connecting member and a short strut assembly.
In accordance with another aspect of the present invention, an expandable stent includes a plurality of expandable cells having at least eight sides and formed by a plurality of alternating long and short, substantially non-deforming struts interconnected by deformable hinges.
In accordance with a further aspect of the present invention, an expandable stent includes a plurality of struts extending substantially longitudinally along an axis of the stent in an unexpanded configuration and a plurality of hinges interconnecting the struts. The plurality of hinges each have a straight active portion which extends substantially circumferentially around the stent in the unexpanded configuration and two curved portions interconnecting the active portion to adjacent ones of the plurality of struts.
In accordance with another further aspect of the present invention, an expandable stent includes a plurality of struts extending substantially longitudinally along an axis of the stent in an unexpanded configuration and a plurality of hinge arrangements interconnecting the struts. Each of the hinge arrangements includes a central portion and four tapered hinges each connected at one end to the central portion and at another end to one of the plurality of struts. Each of the tapered hinges has a smallest width closer to the struts and a largest width closer to the central portion.
In accordance with another aspect of the present invention, an expandable stent includes a plurality of struts extending substantially longitudinally along an axis of the stent in an unexpanded configuration, a plurality of first hinges interconnecting the struts, and a plurality of interconnecting hinge arrangements interconnecting the struts. The plurality of hinges each have a straight active portion which extends substantially circumferentially around the stent in the unexpanded configuration interconnected to adjacent ones of the plurality of struts. Each of the interconnecting hinge arrangements includes a central portion and four second hinges each connected at one end to the central portion and at another end to one of the plurality of struts.